Why are KT88s becoming so popular now?

[Ancient Alien]

Let me count.....
I have 28 KT88 tubes in my amps right now at the studio

For those of you that are slow, that is 7 different amps with 4 KT88's in each

 

[Ancient Alien]

I built this KT88 amp kit last month. It is loud and proud, but mainly a sweet sounding clean amp:

Nice man.
Now go on and build a proper preamp section to feed that bad boy
Can you post some clips of it?

 

[diagrammatiks]

ya that amp up there is missing something like 7 12ax7s

 

[steve_k]

Are KT88's a simple 'drop-in' replacement for EL34's? Or are there concerns over plate voltage, whether or not the PT can take the extra load, bias pot range, etc.? I don't necessarily have it in mind to try them, I'm just curious. Same with KT77's. I had a 6L6 amp that someone put KT66's in, and that was a bad idea. Couldn't bias the amp below 85-87% dissipation, and it put a serious hurtin' on one of the screen grid resistors. (Well, I assume that's what did it... It looked a little toasted and was way out of spec looking at it with an Ohmmeter.)

You got to be careful. The pin out on 88's is different than a 34. In this regard, the 88 need 10V more negative on the bias circuit. Very few amps, will have the bias range to handle this requirement. It is usually a simple bias resistor change or piggybacking parallel resistors to get there.

Steve

 

[Anonymous]

Are KT88's a simple 'drop-in' replacement for EL34's? Or are there concerns over plate voltage, whether or not the PT can take the extra load, bias pot range, etc.? I don't necessarily have it in mind to try them, I'm just curious. Same with KT77's. I had a 6L6 amp that someone put KT66's in, and that was a bad idea. Couldn't bias the amp below 85-87% dissipation, and it put a serious hurtin' on one of the screen grid resistors. (Well, I assume that's what did it... It looked a little toasted and was way out of spec looking at it with an Ohmmeter.)

You got to be careful. The pin out on 88's is different than a 34. In this regard, the 88 need 10V more negative on the bias circuit. Very few amps, will have the bias range to handle this requirement. It is usually a simple bias resistor change or piggybacking parallel resistors to get there.

Steve

KT 88's also draw more filament current. Make sure the power trannie of your amp can handle it before you drop them in or you will hear nothing in a short amount of time...

 

[Anonymous]

I built this KT88 amp kit last month. It is loud and proud, but mainly a sweet sounding clean amp:

Nice man.
Now go on and build a proper preamp section to feed that bad boy
Can you post some clips of it?

Here ya go:

https://www.soundclick.com/bands/page_so ... ID=9846910

 

[jet66]

Are KT88's a simple 'drop-in' replacement for EL34's? Or are there concerns over plate voltage, whether or not the PT can take the extra load, bias pot range, etc.? I don't necessarily have it in mind to try them, I'm just curious. Same with KT77's. I had a 6L6 amp that someone put KT66's in, and that was a bad idea. Couldn't bias the amp below 85-87% dissipation, and it put a serious hurtin' on one of the screen grid resistors. (Well, I assume that's what did it... It looked a little toasted and was way out of spec looking at it with an Ohmmeter.)

You got to be careful. The pin out on 88's is different than a 34. In this regard, the 88 need 10V more negative on the bias circuit. Very few amps, will have the bias range to handle this requirement. It is usually a simple bias resistor change or piggybacking parallel resistors to get there.

Steve

KT 88's also draw more filament current. Make sure the power trannie of your amp can handle it before you drop them in or you will hear nothing in a short amount of time...

Those were pretty much the kind of things I was expecting, thanks for the info. It never seems to be as easily/safely done as some people would lead you to believe. I've seen where people swap these tubes in, and in a lot of cases, I don't think they are aware of the extra strain the 88's can put on their amps, and that they were not designed with them in mind, originally.

 

[racerevlon]

They bring the pain...

 

[blackba]

The family's .... It depends on the amp what ones well work.

KT88/KT90/KT100/6550

EL34/6CA7/KT77

6L6/KT66/5881

KT66 and KT88 are my favorite tubes ..... have been for a lot of years. I like poweramp distortion much better than preamp distortion. Preamp distortion is a often much thinner and smaller sounding with a lack of dynamics (not always). Fryette's last KT88 amp the Sig X is very much about poweramp distortion compared with his other amps. But you are right AA the KT88 is a great tube for a amp that is voiced for preamp distortion.

So is a KT77 a drop in replacement for an EL34 and likewise is a KT66 a drop in replacement for a 6L6?

My friend is retubing a Marshall JVM410, I was recommending SED =C= EL34's to him, now I am wondering if he should consider KT77's...

Honestly until the last few years, I had never heard of a KT66, KT77, KT88, or 6550 tubes. It was only as new suppliers of tube started making them that I started seeing more threads on them. I am late to the party as usual.

 

[Ancient Alien]

So is a KT77 a drop in replacement for an EL34 and likewise is a KT66 a drop in replacement for a 6L6?

My friend is retubing a Marshall JVM410, I was recommending SED =C= EL34's to him, now I am wondering if he should consider KT77's...

Honestly until the last few years, I had never heard of a KT66, KT77, KT88, or 6550 tubes. It was only as new suppliers of tube started making them that I started seeing more threads on them. I am late to the party as usual.

Yes to the above.
To re tube an EL34 amp with KT88's usually only takes adding a new grid resistor in most cases.
KT77's sound excellent in the JVM and other Marshall based amps like Splawn etc.

 

[Ancient Alien]

Here ya go:

https://www.soundclick.com/bands/page_so ... ID=9846910

Very nice playing and tone.

 

[Spaceboy]

I want to slave my Ampeg VH140C preamp into some KT88s out of curiosity.

 

[Anonymous]

I think I remember reading somewhere that, If you have an amp that was designed around EL34's or 6L6's that...You can run KT88's or 6550's once you get the bias resistors sorted out to do so but! You would bias the KT88's or 6550's around the same bias setting as you would the EL34's or 6L6's so's it doesn't put a huge strain on the tranny's...

 

[Loudness250]

I think what the first guy said was pretty accurate, for a long time el34's and 6l6 was all that was being used pretty much. kt88's are great tubes and I think they just rose to the forefront when some manufacturers started using them for there amps and people liked the sound. kt88's are awesome sounding tubes with more power than el34's or 6l6's.

 

[diagrammatiks]

that's not to mention all the other tubes that haven't come back yet.

 

[noob_pwn]

i think KT88's seem to work well for alot of the kind of tones people are going for today, they don't want too much breakup in the power section because they get it from the preamp, and they want the biggest punch and sonic footprint they can find, KT88's fit this bill perfectly and from my experience they are also very reliable.

 

[stephen sawall]

So is a KT77 a drop in replacement for an EL34 and likewise is a KT66 a drop in replacement for a 6L6?

My friend is retubing a Marshall JVM410, I was recommending SED =C= EL34's to him, now I am wondering if he should consider KT77's...

Honestly until the last few years, I had never heard of a KT66, KT77, KT88, or 6550 tubes. It was only as new suppliers of tube started making them that I started seeing more threads on them. I am late to the party as usual.

Yes to the above.
To re tube an EL34 amp with KT88's usually only takes adding a new grid resistor in most cases.
KT77's sound excellent in the JVM and other Marshall based amps like Splawn etc.

I believe this is true in most cases but I have heard of small variances in makes or runs that well not get along with certain amps.

Myself I just ask the builder what well work in them and what they recommend. Most of the time I agree with their taste. Some amps are very much voiced to a tube and most other tubes well not be to the taste of most.

For me it is pretty obvious why people like KT88 .... girth..... well that is why I like them. In the right amp KT88 sound great for poweramp distortion.

 

[RJF]

KT88's are badass. Tighter bottom end, dryer overall tone IMHO, and they help shed some compression too.

When I went from all EL34's to all KT88's in my Herbert I was blown away. I have since added a pair of KT88's and a pair of KT66's to my Dual Rectifier.

 

[Nigel]

Classic Smashing Pumpkins tone was a 100 watt Marshall JCM 800 with KT88's.

 

[billm408]

KT88's are badass. Tighter bottom end, dryer overall tone IMHO, and they help shed some compression too.

I've been running KT88's in my 101b for the last 4 years and they made it a completely different amp- less compressed, tighter low end and punchier mids.